The present invention is directed to a variable capacitor tuning apparatus, and more particularly to a variable capacitor tuning apparatus having an improved tuning head.
A known variable capacitor tuning arrangement 20 previously marketed by Jennings Technology, the owner of this patent, under, for example, model numbers CSVF/I-500-0315 or CVCJ/I-1000-0403 is shown in an exploded view in FIG. 1. The variable capacitor tuning arrangement 20 typically included a variable capacitor 22 and a tuning head 24. The tuning head 24 included a support thrust bearing 26, a sensor mount 28, an adjust plug 30, fiber optic connectors 34, 36 and a lead screw 40.
In implementing the known variable capacitor tuning arrangement 20, a customer would provide an actuator 44, a controller 46, an emitter 48 and a detector 50. In operation, the controller 46, would send commands to the actuator 44, which is a stepper motor. In response to the commands from the controller 46, the actuator 44, which is mechanically coupled to the tuning head 24 via the lead screw 40, would cause the tuning head 24 to change the capacitance of the variable capacitor 22. The tuning head 24 would change the capacitance of the variable capacitor 22 by meshing opposing conductive plates or cylinders to varying depths with respect to one another. The tuning head 24 would provide feedback to the controller 46 to indicate the position of the conductive plates or cylinders with respect to one another.
Referring now to the tuning head 24, the sensor mount 28 was fixed to the support thrust bearing 26. Both the sensor mount 28 and the adjust plug 30 had bores therein to accommodate the fiber optic cables (not shown) connected to the fiber optic connectors 34 and 36. The lead screw 40 extended into the support thrust bearing 26 and engaged the adjust plug 30 so that when the lead screw 40 was turned by the actuator 44, the adjust plug 30 moved closer to, or farther from, the top of the support thrust bearing 26 along the axis of the lead screw 40. The adjust plug 30 was, in turn, coupled to the variable capacitor 22 so that when the adjust plug 30 moved, due to lead screw 40 rotation, the capacitance of the variable capacitor 22 changed.
The emitter 48 provided optical energy to the fiber optic connector 34, which was fixed into the sensor mount 28. Optical energy that was coupled into the fiber optic connector 34 was transmitted to the detector 50, via the fiber optic connector 36 when the fiber optic cables associated with the fiber optic connectors 34 and 36 were aligned. In response to the optical energy, the detector 50 provided an electrical output signal to the controller 46. The vertical position of the adjust plug 30 along the lead screw 40 axis was adjusted so that the fiber optic cable associated with the fiber optic connector 36 was aligned with the fiber optic cable associated with the fiber optic connector 34 when the variable capacitor 22 was tuned to a capacitance value of interest.
The controller 46 was programmed to recognize the signal provided to it by the detector 50 when the fiber optic cables were aligned and optical energy was coupled to the detector 50. As the variable capacitor 22 was tuned away from the capacitance value of interest, the adjust plug 30 moved, the fiber optic cables associated with the fiber optic connectors 34 and 36 were no longer aligned, the detector 50 no longer received optical energy and changed the state of the signal that it provides to the controller 46. Accordingly, the controller 46 could determine whether or not the variable capacitor 22 was tuned to the capacitance value of interest based on the signals provided to it by the detector 50.